There are generally two ways to support patient nutrition for patients who are unable to self-feed orally in the usual manner—parenteral nutrition (by injection, e.g. IntraVenous (IV) feeding of electrolytes), and enteral nutrition (delivery directly into the GastroIntestinal (GI) tract). One disadvantage of IV feeding is that the patient's bowels may eventually shut down for lack of use, especially for patients with extended ICU stays. Enteral nutrition generally provides various physiologic and metabolic benefits as compared to parenteral nutrition. Thus, enteral tube feeding (e.g. NasoGastric (NG) tube feeding) is generally preferred when the patient's GI tract is functional and the patient is unable or unwilling to receive nutrition orally. In enteral tube feeding, a tube such as a NasoGastric (NG) tube is inserted through the patient's nasal passages and into the stomach. Nutrients (usually in the form of formula) is delivered directly to the patient's stomach through the NG tube.
However, enteral tube feeding can cause complications. Some patients receiving enteral tube feeding experience nausea and vomiting (which can lead to aspiration of stomach contents into the lungs and subsequent pneumonia) due to delayed gastric emptying. Even without vomiting, NG tube feeding can cause the contents of the stomach to reflux back into the lungs. When an NG tube is inserted into the stomach, the lower esophageal sphincter at the junction between the esophagus and the stomach may not be able to form an adequate seal, which can again lead to aspiration of stomach contents into the lungs and subsequent pneumonia. Other possible complications include diarrhea, constipation, and malabsorption/maldigestion (impaired absorption of nutrients).
Gastric Residual Volume (GRV) is the volume of residual gastric contents that remain in the stomach after a certain period of time has elapsed from an enteral feeding, and generally is an indication of how well the nutrients (e.g formula) are being absorbed by the stomach. High GRV levels can alert health care providers that there may be complications impairing gastric emptying and impending intolerance, and that subsequent feedings should be reduced or stopped altogether before vomiting or aspiration occurs. However, there is currently no direct and relatively immediate confirmation of emptying of the stomach after formula has been forced into the patient's stomach via an NG tube. Furthermore, even if the stomach empties, it cannot be immediately determined whether the formula is being tolerated (the nutrients are being absorbed), or whether the formula is just passing through the patient's digestive system, resulting in diarrhea, for example. To monitor tolerance and gastric emptying, a process referred to as GRV detection is currently employed.
In current GRV detection methodologies, a syringe or similar device is connected to the NG tube to extract the patient's stomach contents after a certain period of time. The amount of gastric contents extracted at that time is an indication of gastric emptying. The degree of gastric emptying along with other symptoms can provide an indication of gastric tolerance. Elevated GRV levels can be an indication of enteral tube feeding intolerance.
However, because the stomach contents extracted using this GRV detection procedure have an unpleasant odor and can produce biohazards, contamination, bacteria, and infections, there may be a reluctance on the part of the clinician to regularly perform the procedure. In addition, because GRV detection results in the removal of the stomach contents, the patient experiences a loss of nutrition if the gastric contents are not returned to the patient's stomach through the NG tube.
Thus, there is a need to perform GRV detection in a manner that is simpler, less unpleasant, does not produce biohazards, contamination, bacteria, and infections, and does not lead to a loss of nutrition by the patient. Such systems, apparatus and methods may lead to more regular testing of GRV detection, more frequent detection of enteral tube feeding intolerance, and faster implementation of corrective measures.